1-0 Week 1 Overview


Welcome to Week 1

Topics

Learning Objectives


1-1 History of Comms


History of Communication

History of Communication

10 Things You May Not Know About the Pony Express - HISTORY How did pigeons in olden times know which letter had to be delivered where?  Why doesn't it happen now? - Quora Major Disruptions: AusPost Pauses E-Com Parcel Pickup for Melbourne - Power  Retail

History of Communication

An optical telegraph semaphore.

History of Communication

People in a switching office manually switching telephone connections.

1-2 Network Models


Network Models

Peer-to-Peer Network Model (1 of 2)

Peer-to-Peer Network Model (2 of 2)

Client-Server Network Model (1 of 3)

Client-Server Network Model (1 of 3)

Client-Server Network Model (2 of 3)

Client-Server Network Model (3 of 3)

Client-Server Applications (1 of 2)

Client-Server Applications (2 of 2)

Network Services and Their Protocols (1 of 2)

Network Services and Their Protocols (2 of 2)


1-3 Network Models


Network Hardware

LANs and Their Hardware (1 of 4)

LANs and Their Hardware (2 of 4)

LANs and Their Hardware (3 of 4)

LANs and Their Hardware (4 of 4)

MANs and WANs (1 of 2)

MANs and WANs (2 of 2)


Network Diagrams


Network Diagrams (1 of 6)

Network Diagrams (2 of 6)

The output of the N map command displayed in a Power Shell command line window. N map is a powerful networking tool that can be used for network discovery.

Network Diagrams (3 of 6)

A network diagram that shows the devices on a network using symbols from Cisco. The network has a two switches that are serially connected and connected to one of the switches is a wireless access point. A web server cluster and a file server are connected to one of the switches. A printer and a workstation are connected to the other switch. A laptop is connected to the wireless access point. One of the switches is connected to a router that is further connected to a firewall. The firewall connects to the Internet.

Network Diagrams (4 of 6)

Network Diagrams (5 of 6)

A wiring diagram shows multiple devices connected together on a network. The following information is shown in the wiring diagram. There is an 8-port switch that is connected to a Print Server and two File Servers, File Server 1 and File Server 2. There is a 24-port Gigabit switch that is connected to Work stations 1, 2, 3, and 4. A V o I P adapter is present that is connected to Phones 1 and 2. A voice and data gateway device is also present. The V o I P adapter and the voice and data gateway are connected to a P o E and Gigabit switch. An uplink cable from the 8-port Gigabit Switch, the P o E Gigabit Switch, and the 24-port Gigabit Switch connect the switches to a cable modem and switch. A cable connects the modem to a WAN. A Wi-Fi 6 wireless router is additionally connected to the cable modem and switch.

Network Diagrams (6 of 6)

An illustration shows the typical devices that are installed on a rack. They include switches, patch panels, servers, security appliances, and a U P S.

Labelling and Naming Conventions (1 of 3)

Labelling and Naming Conventions (1 of 3)

Labeling and Naming Conventions (2 of 3)

A close up photograph that shows cables terminating in ports in a rack system. The ports have been labeled and the cables themselves have tags on them.

Labelling and Naming Conventions (3 of 3)

A diagram of a Cisco router with labels identifying the ports, slots, and connectors on it. A diagram serves the purpose when labels cannot be fixed on the router itself. The router has 4 ethernet ports. The first one is for the I T department. The second one is for the Accounting department. The third one is for the H R department. The fourth one is for the Sales department. The router has four slots numbered from 0 to 3. Slot 0 is connected to a WAN. Slots 0 to 2 are unlabeled. Other than these, the router has a U S B port and a card slot for compact flash memory. Both of them are unlabeled.

Week 2 Overview


Topics

Learning Objectives


2-1 OSI


The Open Systems Interconnection Model (OSI Model)

The Seven-Layer OSI Model (1 of 2)

Two illustrations showing how a browser and web server communicate with the analogy of the U S Postal Service. In the first illustration, two stacks with multiple layers are shown representing the client system and the server. The client system has the following layers from top to bottom. Browser. Operating System. Hardware. This stack is connected to the server stack with cabling and other network hardware. The server stack has the following layers from top to bottom. Web server. Operating system. Hardware. This way of communication is similar to the U S Postal Service. The browser can be compared to someone posting a letter in a post box. The operating system is comparable to the U S Post Office. The letters are then transported to their destination in trucks which is comparable to computer hardware. The cabling and other network hardware is comparable to the highways and roads on which the Postal Truck travels. The truck reaches the destination Post Office which represents the operating system of the server. The letter is delivered to the receiver in this case which is the server system.

The Seven-Layer OSI Model (2 of 2)

An illustration showing the layers in the O S I model and the software, protocols, and hardware mapped to these layers. The following are the 7 layers in the O S I model. 1. Physical layer. 2. Data link layer. 3. Network layer. 4. Transport layer. 5. Session layer. 6. Presentation layer. 7. Application layer. Layers 1 and 2 pertain to hardware. Layers 3 to 7 pertain to the operating system. On top of the 7th layer are the applications. In layers 1 and 2, we have the hardware and hardware protocols which includes the Ethernet and Wi-Fi. Layer 3 includes the following network protocols. I P. I C M P. A R P. Layer 4 includes the following network protocols. T C P or U D P. Layers 5 to 7 include the T C P and I P suite of protocols embedded in the operating system. The protocols in these layers are the following. H T T P and H T T P S. S M T P, POP, and I MAP. F T P and F T P S. Above the 7th layer where the applications reside, we have the World Wide Web, E-mail, and F T P applications.

Layer 7: Application Layer

Layer 6: Presentation Layer

Layer 5: Session Layer

Layer 4: Transport Layer

Layer 4: Transport Layer

Layer 3: Network Layer

Layer 3: Network Layer

Layer 2: Data Link Layer

Layer 2: Data Link Layer

Layer 1: Physical Layer

Protocol Data Unit or PDU

Summary of How the Layers Work Together

An illustration indicates how the O S I layer works when a request is made by a web browser on a computer to a web server. A browser that makes up the application, presentation, and session layers builds an H T T P message or a payload on the source computer and passes it to the transport layer. The transport layer adds its own header to the payload to make a segment or datagram. The segment is then passed on to the network layer. The network layer adds its header to the segment, thus making a packet. The packet is then sent to the data link layer. The data link layer adds a header and trailer to the packet making a frame. The frame is then passed to the physical layer. The physical layer residing on the Network Interface Card on the computer sends the bits of information in the frame on the network. A switch receives the transmitted bits. The frame is examined by the data link layer in the switch. It looks at the destination MAC address in the frame and sends it on its way. The frame is passed on to the proper port on the switch and it is sent to the next device which is a router. The router has two Network Interface Cards for the two networks it belongs to. Once the frame is received by the physical layer on the router, it is passed on the data link layer. The data link layer removes the header and trailer from the frame and passes the packet to the network layer. The network layer I P program looks at the destination I P address in the packet and determines the next node it needs to send the packet. The packet is then passed on to the data link layer in the second network interface card on the router. The data link layer adds a new header and trailer and includes the MAC address of the next destination node. Then the frame is passed to the physical layer which transmits the bits to the next node. This bits reach the destination Network Interface Card after several iterations of the previous process in which the next destination nodes are determined. The data link layer in the Network Interface Card firmware receives the frame and removes the header and trailer and passes the packet to the network layer. The network layer removes the header and passes the segment to the transport layer. The transport layer removes the header in the segment and passes the payload to the application layer. The message is then presented to the web server application.

2-2 Physical Transmission


Physical Transmission

Transmission Basics

Frequency, Bandwidth, and Throughput

Transmission Flaws (1 of 2)

Transmission Flaws (2 of 2)

Transmission Flaws (2 of 2)

Duplex, Half-Duplex, and Simplex (1 of 2)

Duplex, Half-Duplex, and Simplex (2 of 2)

The Properties dialog box for a Network Adapter that has been opened from the Device Manager utility in Windows 10. In the Properties window, the Advanced tab is displayed. In this tab, a Property list is displayed. One can select Speed and Duplex from this list and change its configuration as required in the Value drop down menu.

Multiplexing (1 of 2)

Multiplexing (1 of 2)

Multiplexing (2 of 2)


2-3 Safety and Troubleshooting Network


Safety and Troubleshooting Network Problems

Safety Procedures and Policies

Emergency Procedures

Emergency Procedures

Safety Procedures (1 of 4)

Safety Procedures (2 of 4)

Safety Procedures (3 of 4)

Safety Procedures (4 of 4)

Troubleshooting Network Problems

9

Network+ Guide to Networks, 6th Edition

Troubleshooting Network Problems

10

Network+ Guide to Networks, 6th Edition

11

Network+ Guide to Networks, 6th Edition

A flowchart of the previously described troubleshooting steps.

3-0 Week 3 Overview


Topics

Learning Objectives


3-1 Infrastructure


Components of Structured Cabling

From the Demarc to a Workstation (1 of 11)

An overview of the main components that make up the network infrastructure in a location. The diagram shows three buildings, building A, B, and C. Each building has a work area with desktop computers on a network that is further connected to an I D F in a data room. The I D Fs of buildings B and C are connected to an M D F in a data room in building A through separate backbones. The I D F of building A connects directly to the M D F. The Demarc further connects to the I S P.

From the Demarc to a Workstation (2 of 11)

From the Demarc to a Workstation (2 of 11)

From the Demarc to a Workstation (3 of 11)

An illustration showing what an ANSI TIA structured cabling looks like inside a building. The diagram shows the plans for two floors of a building. One side of the ground floor contains the main distribution farm with cabling coming in for the entrance facility. The rest of the room is the work area with computers. In the first floor, directly above is the I D F with the cable coming through a vertical cross connect. Wiring goes to the computers in the work area through horizontal wiring.

From the Demarc to a Workstation (4 of 11)

A photograph of a demarc inside a small data room for a campus network. A box is installed on the wall with the fiber cable from the I S P plugging into the box. This is where the I S P's fiber network ends. An ethernet cable coming from the box marks the beginning of the customer's network.

From the Demarc to a Workstation (5 of 11)

A photograph of a rack system in a data room. In the rack are multiple patch panels. Several cables terminate into receptacles in the patch panel.

From the Demarc to a Workstation (6 of 11)

From the Demarc to a Workstation (6 of 11)

From the Demarc to a Workstation (7 of 11)

Two types of schematics that can be used with V o I P equipment. In the first diagram, the telephone company connects to a voice gateway which is further connected to a switch. Several phones and a V o I P P B X are connected to the switch. In the second diagram, the I S P connects to a switch which further connects to a voice gateway. The voice gateway connects to a legacy P B X that further connects to multiple phones. There are advantages and disadvantages to both approaches as indicated in the two diagrams.

From the Demarc to a Workstation (8 of 11)

An illustration of an M D F that forms an extended star topology in a network. The M D F connects to multiple M D Fs, several workstations and a printer. The I D Fs themselves are connected to several workstations and a printer in one case.

From the Demarc to a Workstation (9 of 11)

From the Demarc to a Workstation (10 of 11)

Two photographs showing the types of racks. In the first photograph is a n open two-post rack. In the second photograph is an enclosed four-post rack.

From the Demarc to a Workstation (11 of 11)

A rack layout which has hot and cold air aisles. Cool air is pumped up from one side of the rack and hot air is vented from the other side of the rack.

3-2 Cabling


Cabling (1 of 5)

Cabling (2 of 5)

An illustration that shows how horizontal cabling is used to connect a switch in a data room to multiple workstations. In the data room is a rack system that has multiple switches installed in it. The switches are connected together using cross connects. Individual cables that are 90 meters long go out from the switches and end in standard ANSI TIA wall outlets with a jack. Ten meters of cable connect the jacks on the standard wall outlets with the workstations.

Cabling (3 of 5)

A diagram showing the layout of a typical U T P cabling installation. The diagram shows a work area and a data room. In the data room is an equipment rack that has a switch and a patch panel installed on it. On the wall are more patch panels. A cable connects the patch panel on the wall to the patch panel in the rack. The patch panel on the rack connects to the switch. A cable from the switch connects to the M D F and forms the backbone. Horizontal cabling connects the patch panel on the wall to a standard wall outlet in the work area. A patch cable connects the wall outlet to a workstation.

Cabling (4 of 5)

Cabling (4 of 5)

Cabling (5 of 5)


3-3 Ethernet


Ethernet (1 of 2)

Ethernet (2 of 2)

An illustration showing the fields in an Ethernet 2 frame. The first field is a preamble and S F D that is 8 bytes long. This is followed by a destination address that makes up 6 bytes. Then comes the source address which also makes up 6 bytes. This is followed by the ethernet type which is 2 bytes long. Then, there is the data plus padding which may be between 46 to 1500 bytes. The last field is made of the F C S which is 4 bytes long.

Ethernet and the OSI Model

OSI model layers, where Ethernet exists at the MAC sublayer of the Data Link layer and the Physical layer

Data link layer – Two Sub-layers

Ethernet Frames

Field name

Length

Description

Preamble and SFD

8 bytes

Signals to the receiving node that bytes following this preamble are the actual frame. Not included when calculating a frame’s total size.

Header

Destination address

6 bytes

Provides the MAC address of the recipient of the data frame.

Source address

6 bytes

Provides the MAC address of the network node that originally sent the data.

Type field

2 bytes

Specifies the upper-layer protocol carried in the frame. E.g. an IP packet has 0x0800 in the Type field.

Data

  1. to 1500 bytes
  2. the data is not at least 46 bytes, padding is added to make a minimum of 46 bytes.

Trailer FCS (frame check sequence)

4 bytes

The FCS trailer ensures that the data at the destination exactly matches the data issued from the source using the CRC (cyclic redundancy check) algorithm.

Ethernet Frames

8 bytes

Preamble and SFD

6 bytes

Header

  1. bytes
  2. bytes

46-1500 bytes

Data

4 bytes

Trailer

Screenshot of frame from Wireshark

Types of Ethernet

IEEE Ethernet Standards

IEEE 802 Committee Standards:

Ethernet

Ethernet

CSMA/CD


3-4 Binary


Base 10 Numbers

Image with information that is on the next slide.

Base 10 numbers

Base 10 numbers use place value, for example in a four digit number, the first digit is the thousands place, the second the hundreds, the third the tens, and fourth the ones.

Place value is determined by exponents. The rightmost place is 100 = 1, then, going left, 101 = 10, 102 = 100, and so on.

Base 10 uses ten symbols: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9.

Binary Number System

Binary code for representing letters in the alphabet. E.g. A is represented by 01000001.

Binary numbers are Base 2. Powers of two are used for place values. So the rightmost place value is 20 = 1, then going left 21 = 2, 22 = 4, and so on.

Bits and Bytes

Units

Definition

Bytes (approx.)

Bits (approx.)

Examples

Bit (b)

Binary digit, a 1 or 0

  1. bit
  2. off, open/closed, +5 V or 0 V

Byte (B)

8 bits

1 byte

8 bits

A single character (e.g. “X”) in ASCII code

Kilobyte (KB)

1 kilobyte

= 1024 bytes

  1. bytes
  2. bits

Typical email = 2 KB

10-page doc = 10 KB

Megabyte (MB)

1 megabyte

= 1024 kilobytes

= 1,048,576 bytes

  1. million bytes
  2. million bits

Floppy disk = 1.44 MB

Typical CPU cache = 4 MB

Gigabyte (GB)

1 gigabyte

= 1024 megabytes

= 1,073,741,824 B

  1. billion bytes
  2. billion bits

Typical RAM = 8 GB

Terabyte (TB)

1 terabyte

= 1024 gigabytes

  1. trillion bytes
  2. trillion bits

Amount of data theoretically transmittable in optical fibre in one second.

Some sources will define these units as powers of 1000. So kilobyte = 1000 bytes etc., and will use kibibyte (KiB), mebibyte (MiB), gibibyte (GiB), and tebibyte (TiB) for definition based on 1024.

Converting Binary to Decimal

  1. = 256
  2. = 128
  3. = 64
  4. = 32
  5. = 16
  6. = 8
  7. = 4
  8. = 2
  9. = 1

bit

1

0

1

1

1

0

1

1

exponent

7

6

5

4

3

2

1

0

value

128

64

32

16

8

4

2

1

128

32

16

8

2

1

187

bit

 

 

 

 

 

 

 

 

exponent

7

6

5

4

3

2

1

0

value

128

64

32

16

8

4

2

1

POGIL - Converting Binary to Decimal andDecimal to Binary

bit

 

 

 

 

 

 

 

 

exponent

7

6

5

4

3

2

1

0

value

128

64

32

16

8

4

2

1

POGIL - Converting Binary to Decimal andDecimal to Binary

bit

 1

0

0

1

1

1

0

1

exponent

7

6

5

4

3

2

1

0

value

128

64

32

16

8

4

2

1

128

16

8

4

1

157

Converting Decimal to Binary

  1. = 256
  2. = 128
  3. = 64
  4. = 32
  5. = 16
  6. = 8
  7. = 4
  8. = 2
  9. = 1

Converting Decimal to Binary

Divisor –

Base

Dividend -

Decimal

Remainder –

Binary

Quotient

2

154

154 / 2 = 77 (0 remainder)

77

0

77 / 2 = 38 (1 remainder)

38

1

38 / 2 = 19 (0 remainder)

19

0

19/2 = 9 (1 remainder)

9

1

9 / 2 = 4 (1 remainder)

4

1

4 / 2 = 2 (0 remainder)

2

0

2 / 2 = 0 (0 remainder)

1

0

1 / 2 = 0 (1 remainder)

0

1

10011010

Converting Decimal to Binary

Boolean Logic

The AND operator gives 1 when both its inputs are 1, and 0 otherwise. The OR operator gives 1 if either input is 1, and 0 if both are 0. The XOR operator gives 1 if one input is 1 and the other is 0. The NOT operator takes one input and gives the reverse.

Extras – Binary Numbers


3-5 Collision Domain and Broadcast Domain


Network Devices

2

Collision Domains

3

collision domains

Broadcast Domains

broadcast domains

Switches

5

Switches – Bridging Tables

6

Switches – Bridging Tables

Four nodes connected via switch, each has a unique MAC address
Ethernet frame fields

Switches – Forwarding Decisions

Collisions in Collision Domain

A diagram of an old network where many hosts, servers and network printers are connected via some hubs, creating a single collision domain where only a single device can send data at a time.

Collision Domain Segmentation

Physical layer level devices create one collision domain. Data Link and Network layer devices break up collision domains

Layer 1 Devices Extend Collision Domains

Collision domains are created by hubs and extended by repeaters

Limiting the Collision Domains

Switches, bridges and routers break up collision domains

Limiting the Collision Domains With a bridge

A bridge or switch will break up a collision domain

Broadcasts in a Bridged Environment

A broadcast is picked up by all stations. A broadcast is also forwarded across all bridges whether the receiving host is on the other side of the bridge or not. This eliminates the benefits of having a bridged network.

Routers

Routing

Routing protocols are used between routers to determine paths and maintain routing tables.

After the path is determined a router can route a routed protocol.

Broadcast Domain Segmentation

Welcome to Week 4

Topics

Learning Objectives


4-1 IP Address


Addressing Overview

MAC Addresses (1 of 2)

MAC Addresses (2 of 2)

A network diagram shows a computer sending a message to another computer through a switch. The switch learns the MAC address of the sending device in the following manner. This message is coming into my port 1. It says
the source MAC address is 12 colon 34 colon 56 colon 78 colon A B colon C D. I’ll add that one to my list! The switch knows that the message is address to the computer with the MAC address, W X colon Y X colon 0 9 colon 87 colon 65 colon 43.

IP Addresses

IPv4 Addresses (1 of 4)

IPv4 Addresses (2 of 4)

IPv4 Addresses (2 of 4)

IPv4 Addresses (3 of 4)

IPv4 Addresses (3 of 4)

IPv4 Addresses (4 of 4)

An example of how Port Address Translation or PAT works. A gateway makes use of PAT to keep track of which host needs to receive a response from a web server on the Internet. The illustration shows a private network with four computers having the following I P addresses. 10 dot 1 dot 1 dot 120 to 123. These computers are connected to a router that acts as the router with the I P address 95 dot 52 dot 44 dot 1. The gateway receives the response from a web server on the Internet. The gateway sends the responses to the computers in the private network based on the following PAT translation table in its memory. 10 dot 1 dot 1 dot 120 colon 80 equals 92 dot 52 dot 44 dot 1 colon 8000. 10 dot 1 dot 1 dot 121 colon 80 equals 92 dot 52 dot 44 dot 1 colon 8001. 10 dot 1 dot 1 dot 122 colon 80 equals 92 dot 52 dot 44 dot 1 colon 8002. 10 dot 1 dot 1 dot 123 colon 80 equals 92 dot 52 dot 44 dot 1 colon 8003.

IPv6 Addresses (1 of 2)

IPv6 Addresses (2 of 2)

Types of IPv6 Addresses (1 of 4)

Types of IPv6 Addresses (2 of 4)

An illustration explaining the three types of I P v 6 addresses. The first one is a global address. In a global address, the first 3 bits begin with 0 0 1. This is followed by the global routing prefix which makes up 45 bits. This is followed by the subnet I D which is 16 bits long. The last set of 64 bits makes up the interface I D. The second type of I P v 6 address is the link local address. This address contains two sets of 64 bits. An example for the set of 64 bits is something like F E 80 colon colon back slash 64. The next set of 64 bits makes up the interface I D. The third type of I P v 6 address is the loopback address. The first section of this address is 127 bits long and there is a final 1 bit section. An example shows the first 127 bits containing zeroes in all places and the final 1 bit containing 1.

Types of IPv6 Addresses (3 of 4)

The result of running the i p config command in the Power Shell command line window in Windows 10. The output indicates that an I P v 6 address has been assigned to a virtual interface. An I P v 4 address has been assigned to this interface as well. An I P v 6 address has been assigned to the physical Wi-Fi interface. An I P v 4 address has also been assigned to this physical Wi-Fi interface.

Types of IPv6 Addresses (4 of 4)


4-2 The Domain Name System (DNS)


Ports and Sockets (1 of 2)

Ports and Sockets (2 of 2)

An illustration that shows how the telnet service works. A client computer requests for a telnet connection on port 23 from a server computer. The server computer responds by sending an acknowledgement for the connection with port 23.

Domain Names and DNS (1 of 2)

Domain Names and DNS (2 of 2)

Namespace Databases

Name Servers (1 of 4)

Name Servers (1 of 4)

Name Servers (2 of 4)

An illustration showing the hierarchy of name servers on the world wide web. At the top of the hierarchy are the D N S root servers. Below the root servers are the top-level domain or T L D servers, some of which are dot com, dot o r g, and dot e d u. Below the T L D servers are the authoritative servers. Under the dot com T L D we have the Microsoft, amazon, and google authoritative servers. Under the dot o r g T L D we have the s t Jude and p b s authoritative servers. Under the dot e d u T L D we have the u a and m d c authoritative servers.

Name Servers (3 of 4)

A network diagram that shows how the queries for the website w w w dot m d c dot e d u is resolved on the Internet. This is a process know as name resolution. A client computer such queries a server which is a local D N S name resolver. The local D N S name resolver passes the query to the root D N S name server. The result of this query is passed on to the local D N S name resolver. The local D N S name resolver then queries the T L D D N S name server for dot e d u. This server responds with the required information. The local D N S name resolver now contacts the authoritative D N S name server for m d c dot e d u. Once, the response is received, it is sent to the client computer by the local D N S name resolver.

Name Servers (4 of 4)

Name Servers (4 of 4)

Resource Records in a DNS Database

Resource Records in a DNS Database

DNS Server Software


4-3 Addressing issues


Troubleshooting Address Problems

The Event Viewer window from Windows 10 that displays a list of administrative events that have occurred on a computer. A printer problem is listed and a diagnosis is provided for the same. The steps to fix the problem are also listed.

Troubleshooting Tools (1 of 8)

Troubleshooting Tools (2 of 8)

Troubleshooting Tools (3 of 8)

Troubleshooting Tools (4 of 8)

The output of executing the i p config with the forward slash all switch is displayed in a Power Shell command line window. More information that using the i p config command is displayed. The MAC address used by the Wi-Fi adapter, the I P address of the D H C P server and D N S server are displayed.

Troubleshooting Tools (5 of 8)

Troubleshooting Tools (6 of 8)

The output of running the host name command in a terminal window with different arguments on a Linux Virtual Machine is demonstrated. The hostname command in itself displays the name of the computer as jill west hyphen Virtual hyphen Machine. The command host name hyphen uppercase A displays the fully qualified domain name of the computer as jill west hyphen Virtual hyphen Machine dot m s home dot net. The command host name hyphen uppercase I displays the I P address of the system as 192 dot 168 dot 201 dot 186. The host name of the computer is changed by entering the command sudo host name jill west. After changing the host name, entering the command host name displays the host name of the computer as jill west.

Troubleshooting Tools (7 of 8)

Troubleshooting Tools (7 of 8)

Troubleshooting Tools (8 of 8)

Common Network Issues (1 of 2)

Common Network Issues (2 of 2)